I have two Adapt-A-Roll 620s in 4x5, only one of which I particularly need. I was thinking of converting the spare to 3A format to use with a Premo #8. This would require narrowing it by around a half inch, and lengthening it by about the same.

(I would probably find a local machine shop to do this for me, rather than attempt it myself.)

So narrowing it would be fairly easy; simply mill off a quarter inch, more or less, from each side, until it matches the original Premo film-pack holder. The "wings" are hollow; it shouldn't be much trouble.

Lengthening it might be more of a hassle. My first thought was to have them drill and tap a couple holes in the end and screw on a piece of aluminum bar stock, but then I took another look at the thing and had an idea.

There's a ridge on the bottom side that stops it when sliding it into a Speed Graphic. If I were to mill that off, the holder would slide in another half inch and bottom out in the camera. (The Premo has a piece of wood at the end of the channel, which the SG does not.)

So my question is: Is that ridge necessary for anything else besides stopping the holder from sliding in too far? Like a light trap or something? Because if so, I could probably get them to attach a similar ridge at the extreme end of the wider part, but if it's not needed, I wouldn't bother.